A semiconductor memory device generally comprises a plurality of memory cells which are used to store a large quantity of information. Each memory cell includes a capacitor for storing electric charge and a corresponding field effect transistor for opening and closing charging and discharging passages of the capacitor. As the size of semiconductor devices continues to shrink, the area occupied by each component of a semiconductor device should be decreased. Capacitors are one component that can occupy considerable area on a semiconductor die depending on the size of the capacitor and/or the number of capacitors on the die.
One example of a capacitor used in a semiconductor memory device is a metal-insulator-metal (MIM) capacitor. A traditional MIM capacitor is two-dimensional (2D). A 2D MIM capacitor has two facing metal plates which are planar and substantially parallel to each other and to the substrate. One method of increasing the capacitance of a MIM capacitor is to increase the sizes of the metal plates. However, increasing the sizes of the metal plates will consume more surface area of the substrate. Accordingly, a need exists to reduce the surface area on the substrate occupied by a capacitor without sacrificing the capacitance.
Accordingly, the inventors have developed an improved 3-dimensional metal-insulator-metal (3D MIM) capacitor and method of forming a 3D MIM capacitor.